slightly lower than 35% and 30% for vibrating energy of 6
and 36 kN m/m2, respectively. The designed void of 0.25 is
obtained with the use of SP. Slightly higher void ratio is
obtained for concrete with no admixture and with WR with
the vibrating energy of 90 kN m/m2. The result confirms
that for a wide range of designed mix proportions, the
vibrating energy of 90 kN m/m2 is suitable as far as total
void is concerned.
The relationship between vibrating energy and compressive
strength is given in Fig. 5. Compressive strength
increases with an increase in vibrating energy as a result
of a reduction in void. The obtained strength is also dependent
on the flow value of paste and type and amount of
admixture used. The strength is slightly higher with the
use of paste of higher flow. The strengths of 13–17, 15–18
and 15–22 MPa are obtained with paste of flow values of
150, 190 and 230 mm, respectively. For each flow value,
higher strength concrete is obtained with the use of admixtures.
The use of WR slightly increases the strength,
whereas the use of SP significantly increases the strength
and the increase is more with an increase in dosage. The
result again suggests that the designed mix proportions,
vibrating energy of 90 kN m/m2 and 1.0% SP are suitable
as far as strength is concerned.